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Segment Routing: IPv6 World Congress 2013
 

Segment Routing: IPv6 World Congress 2013

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Segment Routing: IPv6 World Congress 2013 Segment Routing: IPv6 World Congress 2013 Presentation Transcript

  • Segment Routing – IPv6A stateless solution for IPv6 Traffic EngineeringClarence Filsfils – cf@cisco.comDistinguished Engineer© 2013 Cisco and/or its affiliates. All rights reserved. 1
  • Introduction© 2013 Cisco and/or its affiliates. All rights reserved. 2
  • © 2013 Cisco and/or its affiliates. All rights reserved. 3
  • •  Leverage the classic IPv6 dataplane –  only use the SR extension when needed•  Provide backward compatibility –  incremental deployment –  support non-SR intermediate nodes© 2013 Cisco and/or its affiliates. All rights reserved. 4
  • •  Provide a simple stateless IPv6 Traffic Engineering solution –  less protocols to operate (avoid RSVP-TE) –  avoid millions of tunnels to configure –  avoid 100.000 of tunnel states on core routers•  Automated FRR for any topology© 2013 Cisco and/or its affiliates. All rights reserved. 5
  • •  Applications must be able to interact with the network –  cloud based delivery –  internet of everything•  Programmatic interfaces and Orchestration –  Necessary but not sufficient•  The network must respond to application interaction –  Rapidly-changing application requirements –  Virtualization –  Guaranteed SLA and Network Efficiency© 2013 Cisco and/or its affiliates. All rights reserved. 6
  • •  Simple to deploy and operate –  Leverage IPv6 dataplane –  Leverage Leancore hardware optimization –  Straightforward ISIS/OSPF extension•  Stateless IPv6 Traffic Engineering solution –  provide for optimum scalability, resiliency and virtualization•  Perfect integration with application –  simple network, highly programmable –  responsive to rapid changes© 2013 Cisco and/or its affiliates. All rights reserved. 7
  • •  SR EFT is available! –  12k, ASR9k, CRS1, CRS3 –  MPLS dataplane in current eft image•  Working aggressively with lead customers towards productization© 2013 Cisco and/or its affiliates. All rights reserved. 8
  • •  Simple ISIS/OSPF extension•  Welcoming contribution© 2013 Cisco and/or its affiliates. All rights reserved. 9
  • •  Ahmed Bashandy•  Bertrand Duvivier•  Clarence Filsfils•  Dan Frost•  David Ward•  Mark Townsley•  Stefano Previdi•  Stewart Bryant© 2013 Cisco and/or its affiliates. All rights reserved. 10
  • Segment RoutingConceptual Model© 2013 Cisco and/or its affiliates. All rights reserved. 11
  • •  Forwarding state (segment) is established by IGP –  Agnostic to forwarding dataplane: IPv6 or MPLS –  RSVP-TE is not required•  Source Routing –  source encodes path as an ordered list of segments –  two segments: node or adjacency•  IPv6 SR Routing Extension header –  includes the list of segments•  Tunneled solution –  outer header protects the SR extension header – security –  caches the active SID in the outer DA for backward compatibility© 2013 Cisco and/or its affiliates. All rights reserved. 12
  • IPv6 packet•  The vast majority of the IP traffic travels on ECMP-aware shortest-path.•  SR header is obviously not needed for this case•  Plain classic IPv6 packet© 2013 Cisco and/or its affiliates. All rights reserved. 13
  • SR header {sid1, sid2, sid3, ptr} IPv6 packet•  SR header is present only for the subset of the traffic that requires source routed explicit path•  SR header contains –  ordered list of segment –  pointer identifying the active segment –  forwarding decision is based on the active segment© 2013 Cisco and/or its affiliates. All rights reserved. 14
  • A packet injected at A B C D node C with active 9003 Z 65 segment 9003 is forced through M N O P datalink CO•  C allocates a local segment for its datalink adjacency CO•  C advertises the adjacency segment in ISIS –  simple sub-TLV extension•  C is the only node to install the adjacency segment in SR dataplane© 2013 Cisco and/or its affiliates. All rights reserved. 15
  • {9101,{9101, 9107, 9103, 9105} 9105} 9105, 9105, 9107, 9103, B C D 9101{9101, 9105, 9107, 9103, 9105} 9105 A 9107 Z N O P 9105 9103 {9101, {9101, 9107, 9103, 9105} 9105} 9105, 9105, 9107, 9103,•  Source routing along any explicit path –  stack of adjacency segments•  SR provides for entire path control© 2013 Cisco and/or its affiliates. All rights reserved. 16
  • Pop 9003 9001 switches on blue member Pop 9001 B C 9002 switches on green member Pop 9002 9003 load-balances on any Pop 9003 member of the adj•  Adjacency segment represents a specific datalink to an adjacent node•  Adjacency segment represents a set of datalinks to the adjacent node© 2013 Cisco and/or its affiliates. All rights reserved. 17
  • •  Node SR Range –  a range of globally unique segments allocated to nodes –  e.g. [64, 5000]•  Each node gets one unique segment from SR Range –  Node Z gets segment 65© 2013 Cisco and/or its affiliates. All rights reserved. 18
  • A B C D A packet injected Z 65 anywhere with active M N O P segment 65 will reach Z via ecmp- aware shortest-path•  Z advertises its node segment –  simple ISIS sub-TLV extension•  All remote nodes install the node segment to Z in the SR dataplane© 2013 Cisco and/or its affiliates. All rights reserved. 19
  • B C D A packet injected A Z 65 anywhere with active N O P segment 65 will reach Z via ecmp- aware shortest-path•  Z advertises its node segment –  simple ISIS sub-TLV extension•  All remote nodes install the node segment to Z in the SR dataplane© 2013 Cisco and/or its affiliates. All rights reserved. 20
  • •  ECMP-aware shortest-path to a node© 2013 Cisco and/or its affiliates. All rights reserved. 21
  • 72 72 A B C D Z 9003 65 M N O P 65•  Source Routing•  ABCOPZ is expressed as {72, 9003, 65}© 2013 Cisco and/or its affiliates. All rights reserved. 22
  • {72, 78, 65} 72 72 A B C D 78 Z 65 M N O P 65•  Node Segment is at the heart of the proposal –  ecmp multi-hop shortest-path –  in most topologies, any path can be expressed as list of node segments© 2013 Cisco and/or its affiliates. All rights reserved. 23
  • Nodal segment to C Nodal segment to C A B C D Adj Segment Z M N O P Nodal segment to Z•  Simple extension•  Excellent Scale: a node installs N+A FIB entries –  N node segments and A adjacency segments© 2013 Cisco and/or its affiliates. All rights reserved. 24
  • •  IP-based FRR is guaranted in Backbone any topology –  2002, LFA FRR project at Cisco C1 C2 –  draft-bryant-ipfrr-tunnels-03.txt•  Directed LFA (DLFA) is E1 E4 guaranteed when metrics are symetric 1000 E2 E3•  No extra computation (RLFA) Adj segment Node segment to P node to Q node•  Simple repair stack –  node segment to P node –  adjacency segment from P to Q Default metric: 10© 2013 Cisco and/or its affiliates. All rights reserved. 25
  • Segment RoutingIPv6 dataplane© 2013 Cisco and/or its affiliates. All rights reserved. 26
  • SRB-64bit-Block Active SID Flags Entropy 0xCAFFE0123456789A 32bits 8 bits 24bits•  SR domain dedicates an /64 block for SR –  called the SR block SRB (e.g. 0xCAFFE0123456789A/64) –  other block length would work•  All nodes within domain are configured with SRB block•  The SID is found within the address•  Backward compatibility –  Intermediate Non-SR-capable nodes switch the traffic classically© 2013 Cisco and/or its affiliates. All rights reserved. 27
  • SRB-64bit-Block Active SID Flags Entropy 0xCAFFE0123456789A 32bits 8 bits 24bits•  Upon receiving a packet, an SR node checks whether the DA is within the SRB block•  If yes, it forwards on the 32-bit SID –  leancore performance improvement –  it uses the 24-bit entropy to feed ECMP selection >  ECMP efficiency is preserved despite the outer tunnel© 2013 Cisco and/or its affiliates. All rights reserved. 28
  • V/v Inner packet I E destined to V/v IPv6 outer header from IS to ES SR domain•  A packet which requires Source Routing is tunneled from I to E© 2013 Cisco and/or its affiliates. All rights reserved. 29
  • {v6, TC’, FL’, PL’, NH=43, HL’, 0xCAFFE0123456789A-SIDI, 0xCAFFE0123456789A-SID1} {t=T, NH=6, ptr, SID1, SID2, SID3} {v6, TC, FL, PL, NH, HL, S, D, payload} sid3 I E sid2 S sid1 D{v6, TC, FL, PL, NH, HL, S, D, payload} {v6, TC, FL, PL, NH, HL, S, D, payload}© 2013 Cisco and/or its affiliates. All rights reserved. 30
  • F sidE D G I A E sidC sidF B CS D•  Intermediate nodes switch on outer header only –  A, B, D, G do not process the SR extension header –  A, B, D, G could be SR-non-capable© 2013 Cisco and/or its affiliates. All rights reserved. 31
  • F sidE D G I A E sidC sidF B CS D•  Ingress node pushes the outer and SR headers and set the outer DA address to the first SR hop: SID-C•  Egress node pops the outer and SR headers© 2013 Cisco and/or its affiliates. All rights reserved. 32
  • F sidE D G I A E sidC sidF B CS D•  Intermediate segment switching routers update –  the pointer in the SR extension header –  the outer DA address to the next segment© 2013 Cisco and/or its affiliates. All rights reserved. 33
  • •  The operator or the SDN controller programs the ingress node to classify a specific flow and encapulate it with the SR source route•  The core of the network is not aware of anything•  A core node only installs –  N node segments –  A local adjacency segments•  Any route can be expressed based on these N+A segments•  Millions of flows can be engineered•  Frequent re-optimizations is possible© 2013 Cisco and/or its affiliates. All rights reserved. 34
  • Use cases© 2013 Cisco and/or its affiliates. All rights reserved. 35
  • •  An SR core router scales much than with RSVP-TE –  The state is not in the router but in the packet –  N+A vs N^2 N: # of nodes in the network A: # of adjacencies per node © 2013 Cisco and/or its affiliates. All rights reserved. 36
  • SR avoids state in the core SR avoids enumerating RSVP-TE tunnels for each ECMP paths•  A sends traffic with [65] Classic ecmp “a la IP”•  A sends traffic with [111, 65] Packet gets attracted in blue plane and then uses classic ecmp “a la IP”© 2013 Cisco and/or its affiliates. All rights reserved. 37
  • •  Tokyo to Brussels –  data: via US: cheap capacity –  voip: via russia: low latency•  CoS-based TE with SR –  IGP metric set such as >  Tokyo to Russia: via Russia Node segment to Brussels >  Tokyo to Brussels: via US Node segment to Russia >  Russia to Brussels: via Europe –  Anycast segment “Russia” advertised by Russia core routers•  Tokyo CoS-based policy –  Data and Brussels: push the node segment to Brussels –  VoIP and Brussels: push the anycast node to Russia, push Brussels© 2013 Cisco and/or its affiliates. All rights reserved. 38
  • B C D 9101 9101 9101 9105 9105 9107 A 9107 Z 9105 9103 9105 N O P 9101 9103•  For Traffic Engineering•  or for OAM Nanog57, Feb 2013© 2013 Cisco and/or its affiliates. All rights reserved. 39
  • •  The state is not in the router•  The state is in the packet•  The packet travels with its complete state –  entry point and exit points –  intermediate path up to the midpoint –  remaining path to the exit point –  better than MPLS dataplane!•  Many OAM and billing applications possible•  Many service enforcement applications possible© 2013 Cisco and/or its affiliates. All rights reserved. 40
  • 65 2G from A to Z please FULL 65 Link CD is full, I cannot use the shortest-path 65 straight to Z•  The network is simple, highly programmable and responsive to rapid changes –  perfect support for centralized optimization efficiency, if required© 2013 Cisco and/or its affiliates. All rights reserved. 41
  • Tunnel AZ onto {66, 68, 65} 66 FULL 68 65 Path ABCOPZ is ok. I account the BW. Then I steer the traffic on this path•  The network is simple, highly programmable and responsive to rapid changes© 2013 Cisco and/or its affiliates. All rights reserved. 42
  • Conclusion© 2013 Cisco and/or its affiliates. All rights reserved. 43
  • •  Simple to deploy and operate –  Leverage IPv6 dataplane –  Leverage leancore hardware optimization –  straightforward ISIS/OSPF extension•  Stateless IPv6 Traffic Engineering solution –  provide for optimum scalability, resiliency and virtualization•  Perfect integration with application –  simple network, highly programmable –  responsive to rapid changes© 2013 Cisco and/or its affiliates. All rights reserved. 44